I think I might have a problem with my video card

I installed a new video card a few months ago, it works great.
I used my computer last night and it worked fine. This morning I tried to turn on my computer, the tower turns on fine, the monitor however is black, it says no input signal and goes into sleep mode as if the tower isn't even plugged in.

I have tried connecting it to a different monitor but I get the same problem, so the monitor must be fine
I used the cable (vga i think) from the other computer I borrowed the monitor from in my second attempt but I have the same problem
In a third attempt I put on some latex gloves, turned the tower off, removed the side lid, the plugged the power cable back in and turned it on - the power light turns green, the main fan and video card fan start up - so the power supply in the tower must work.

It could be the adapter between the video card and the (vga i think)cord that connects to the monitor, but I do not have another adapter to try it with